Experts added, though, that while a 6.9 magnitude quake is technically considered grounds for a tsunami warning, it does not mean a tsunami will pose a large threat.

Rhett Butler, geophysicist at the University of Hawaii Manoa, says last month's 6.9 event was small.

"You could detect it but it was not large enough to be a concern," he said.

That quake was something called a thrust event, which is especially typical for creating tsunamis, Butler said. Thrust events deform the seafloor after one tectonic plate is forced under another. These events produce some of the most powerful earthquakes in the world.

"If it had been a magnitude 7.9 event, it would have had a much more serious event," Butler said.

Such an event is not completely out of the question, he added.

"It is conceivable that you could get a large earthquake in the area," he said, adding that a bigger seismic event would "not be unexpected."

The U.S. Geological Survey says the most recent and destructive tsunami in Hawaii was a magnitude 7.7 earthquake off Kilauea's south flank in 1975.